1. Field of the Invention
This invention relates to a conduit cleaner that at least one of a) breaks up foreign matter within a conduit and b) discharges a fluid under pressure to effect cleaning of the inside walls of a conduit and, more particularly, to a skid assembly that guides movement of the conduit cleaner within a conduit.
2. Background Art
Conduit cleaners, such as those used to sever/break up foreign matter within a conduit and scour the inside walls of a conduit, are well known in the art. One highly successful conduit cleaner is disclosed in U.S. Pat. No. 3,740,785, to Latall.
The Latall conduit cleaner has a subassembly consisting of a thruster section and a motor. High pressure water is delivered to the thruster section and is expelled through jet passages radially outwardly and rearwardly so as to both propel the unit and scour the inside surface of the conduit within which the unit resides. The pressurized water supply simultaneously communicates with the motor to effect operation thereof and cause rotation of a root cutter blade at the leading end of the unit.
To facilitate translation of the unit through a conduit, a cage-like skid assembly is provided, which assembly includes a plurality of circumferentially spaced runners/skids. The runners are elongate in the direction of travel and have radially inturned ends to limit the possibility of hangup as the unit advances in, or is withdrawn from, a conduit.
The runners are fixedly attached to a split clamp through intermediate struts so that the entire skid assembly remains intact as it is assembled to, and disassembled from, the motor/thruster section subassembly. For rigidity, the runners are made from heavy gauge rods that are welded fixedly to the struts, which in turn are welded to the split clamp.
While the Latall unit has been highly successful, there are some drawbacks with the skid assembly. More particularly, the runners on the skid assembly are in fixed relationship so that they cooperatively produce but one effective diameter. In certain environments, it may be desirable to enlarge or diminish the effective diameter of the skid assembly. The Latall unit requires that the skid assembly be separated as a unit and replaced with a different, fully assembled skid assembly having different dimensions.
To separate the skid assembly, a bolt is loosened, which allows the clamp to be enlarged and thereby slid along the motor housing and over the thruster section. This operation requires that the supply line be taken off of the thruster section. Alternatively, the cutting blade assembly at the leading end of the unit can be separated from the driving motor, thereby allowing the skid assembly to shift forwardly off of the unit.
While the removal of one skid assembly and replacement thereof with another skid assembly can be accomplished, this procedure is relatively complicated and time consuming. Several tools are required to disconnect the supply line, remove the cutting blade assembly, and loosen the split clamp. When this change is made out in the field, considerable down time may result.
Another problem with the Latall structure is that, if the effective diameter of the skid assembly is to be altered, the user must keep one or more extra, self-contained skid assemblies on hand. These highly rigid skid assemblies are relatively expensive to manufacture and take up a considerable amount of space.
Another problem with the Latall unit is that it is prone to hanging up on obstructions within the conduit as it is being withdrawn. The unit may, for example, hang up on any step that is in the conduit, on a root, or on severed foreign matter that resides within the conduit.